The present invention relates to a simulator for automatic printing apparatus and, more particularly, to a simulator for automatic photographic color printing apparatus which is adapted to produce, from a negative film as same image as that which will be printed on a photographic paper by an automatic photographic printing apparatus, and for displaying the thus produced image on a CRT.
Automatic photographic color printing apparatuses have been known in which a negative color film is printed and then developed such that all of the print copies have same photographic density and color balance irrespective of the density of the negative (i.e., underexposed, optimum-exposed or overexposed negative) by correcting the density using the integral transmission density (LATD) of the entire image in the negative color film, and by performing slope control thereon. Such an automatic photographic color printing apparatus generally comprises a light source, a light adjusting filter, a mirror box, a negative carrier, and an optical system having a black shutter, which are aligned in the apparatus in that order. In order to print a negative color film, the negative color film supported by the negative carrier is irradiated by the light source, and the black shutter is opened for a predetermined period of time (the exposure time is made constant) so that the image in the negative color film is formed on a sheet of photographic paper. The photographic paper on which the image of the color negative has been formed is then automatically developed by a developing process so that it becomes a print copy. In the automatic photographic printing apparatus of this type, the light transmitted through the negative is broken down into primary colors including red light (R), green light (G), and blue light (B) by the light receiving element. The density of each primary color is controlled using the LATD on the basis of the Theorem of Evans, while the slopes of the three primary colors are controlled so as to be the same, so as to control the color balance.
With this automatic photographic printing apparatus, all a the prints exhibit the same levels of density and color balance, unless a change is caused in the conditions of the developing process.
However, if the major subject in the color negative has the optimum density but the density of its background is higher or lower, the density of the background affects the exposure, resulting in density failure. The difference in color balance between the major subject and the background, e.g., the complementary relationship between the colors of the major subject and the background, may produce color failure. In such a case, density correction or slope control will not ensure a print copy of excellent quality, and the negative must be printed and developed again.
To obviate this problem, Japanese Pat. Laid-Open (Kokai) No. 53-46731 a photographic inspection device provided with a simulator which is capable of displaying on a TV screen the image in a negative which is reproduced via a TV camera. In this device, the color video signals are adjusted such that the image displayed on the TV screen has a desired density and color balance, and these adjusted color signals are employed to print the negative in an automatic photographic printing apparatus. Further, in the automatic photographic apparatus disclosed in the specification of Japanese Pat. Publication No. 42-25220, the image in a negative which is to be printed on-the photographic paper is displayed on a TV screen, and the automatic exposure device is coupled to the resistors for adjusting the brightness and contrast of the TV. In either case, the image is simulated so as to reduce the frequency with which reprinting redeveloping has to be resorted to.
The first method which employs the photographic printing apparatus, however, encounters a problem in that, since different light sources are used for the photographic inspection device and for the simulator for the automatic photographic printing apparatus, conditions such as the density and color balance of the image printed on a photographic paper by the automatic photographic printing apparatus in accordance with the data derived from the inspection device often differ from those displayed on the TV screen, due to, for example, fluctuations in the states of the light sources. On the other hand, the following problem is involved in the second apparatus in which the automatic exposure device is coupled to the resistors for adjusting the brightness and contrast of the TV. Namely, since this arrangement merely controls the TV signal in such a way as to enable the TV screen to display the optimum image, despite the difference in the coloring characteristics as between the TV screen and the photographic paper, the image displayed on the TV screen is different in quality from that actually obtained on the photographic paper after the printing.
It is also to be pointed out that, the conventional apparatus requires that a negative/positive inversion be conducted for the purpose of attaining grey hue matching in the printing coloring characteristics, through effecting multiplication b-.gamma., after attaining hue matching between the negative image and the positive image. The hues are undesirably changed as a result of the negative/positive inversion, so that it is necessary to again conduct the hue matching operation. In consequence, a complicated operation is required to adjust the parameters which are necessary in attaining the hue matching.